A conventional security system for residence discloses in U.S. Pat. Nos. 7,113,099 and 5,689,235 which generally consists of a system host, various types of sensors, monitor video cameras and various types of alarms. These devices are communicated through radio frequency signals. In the past, when the system host is in an alert condition, namely people are absent from the house, commands have to be entered in advance on the keyboard of the system host to make all the sensors and alarms under the control of the system host to enter an alert condition to guard against intruders or detect risky environmental conditions. When the people of the house return or are resting indoors at night, the alarms and sensors cannot be all set ON, otherwise the sensors in the house could be mistakenly triggered to generate a faulty alarm. Hence the system host should be able to selectively actuate the sensors. While such a technique resolves the problem of triggering faulty alarm, it also creates other problems to users. Because the sensors have to be selectively actuated, all the alarms and sensors have be coded and numbered. And the individual numbers of the alarms and sensors have to be entered on the keyboard of the system host according to requirements so that the computer of the system host can determine which alarms and sensors to be set ON and OFF. In a smaller space in which the number of the alarms or sensors is smaller, a user can set the required sensors based on his/her memory. In the event that the scope of security alarm is greater, and the number of sensors increases. To set the required sensors not only has to rely on user's memory but also has to enter the number of the individual sensors into the system host. It is tedious and takes a lot of time. At present setting a complete security system still has to rely on the technicians of the security service provider. The service fee is charged according to the service content. Altering system procedures incurs additional expense to house owners. Alteration of the security system also cannot be done instantly according to requirement.